I think he's pretty aware of effect systems. He talks about them in his podcast, for example. Roc, as a descendant of Elm, is trying to avoid using too much jar

I think he's pretty aware of effect systems. He talks about them in his podcast, for example. Roc, as a descendant of Elm, is trying to avoid using too much jargon and explain what you can do with it, rather than scaring beginners away with technical jargon.